Among the conventionally-known techniques related to lamps mounted on vehicles (i.e., vehicle lamps) is one disclosed in Patent Literature 1.
The vehicle lamp disclosed in Patent Literature 1 is for use as a blinker lamp of an automotive vehicle and includes a light source, and a light guide member for guiding light emitted by the light source. The light guide member has a plurality of recess-shaped portions formed therein perpendicularly to a traveling direction of light. Pitches between the recess-shaped portions progressively narrow or decrease as distances, from the light source, of the recess-shaped portions increase, i.e., with the increasing distance from the light source.
Light within the light guide member reflects toward outside at positions where the recess-shaped portions are formed. Energy of the light is great in the neighborhood of the light source, and thus, sufficient light can be secured with a small number of the recess-shaped portions formed in that neighborhood. The light energy decreases with the increasing distance from the light source. Therefore, in such a distant area, a greater number of recess-shaped portions are formed so that more light can be reflected and thus necessary light can be secured. With the vehicle lamp constructed as above, the entire light guide member can be illuminated uniformly.
Such a vehicle lamp has a function of allowing a person (or persons) outside the vehicle to recognize the vehicle. In order to allow a person outside the vehicle to recognize the vehicle, it is desirable that the light guide member can be illuminated uniformly and in various illumination styles.